The present invention contemplates methods of producing a recombinant protein comprising fermenting a prokaryotic host cell wherein said prokaryotic host cell has been transformed with a nucleic acid encoding said recombinant protein, harvesting said recombinant protein under conditions where dO2 levels are greater than 0%, purifying said recombinant protein to a filtered bulk, wherein said filtered bulk does not contain detectable DHNA-recombinant protein adduct, as measured by an IEC assay at 310 nm. Furthermore, method of producing a recombinant protein comprising fermenting a menE gene-deleted prokaryotic host cell wherein said prokaryotic host cell has been transformed with a nucleic acid encoding said recombinant protein, harvesting said recombinant protein, purifying said recombinant protein to a filtered bulk, wherein said filtered bulk does not contain detectable DHNA-recombinant protein adduct, as measured by an IEC assay at 310 nm, wherein the recombinant protein yield is increased by about 20% or greater is contemplated.